Fifty years of the 137°E repeat hydrographic section in the western North Pacific Ocean     

Eitarou Oka  Masao Ishii  Toshiya Nakano  Toshio Suga  Shinya Kouketsu  Masatoshi Miyamoto  Hideyuki Nakano  Bo Qiu  Shusaku Sugimoto  Yusuke Takatani 《Journal of Oceanography》2018,74(2):115-145

The 137°E repeat hydrographic section of the Japan Meteorological Agency across the western North Pacific was initiated in 1967 as part of the Cooperative Study of the Kuroshio and Adjacent Regions and has been continued biannually in winter and summer. The publicly available data from the section have been widely used to reveal seasonal to decadal variations and long-term changes of currents and water masses, biogeochemical and biological properties, and marine pollutants in relation to climate variability such as the El Niño-Southern Oscillation and the Pacific Decadal Oscillation. In commemoration of the 50th anniversary in 2016, this review summarizes the history and scientific achievements of the 137°E section during 1967–2016. Through the publication of more than 100 papers over this 50-year span, with the frequency and significance of the publication increasing in time, the 137°E section has demonstrated its importance for future investigations of physical–biogeochemical–biological interactions on various spatiotemporal scales, and thereby its utility in enhancing process understanding to aid projections of the impact of future climate change on ocean resources and ecosystems over the twenty-first century.  相似文献   

东海和冲绳沉积物中自生铀蓄积过程及控制机理     

王中良  刘丛强  朱兆洲  山田正俊 《地球化学》2006,35(3):240-248

采用同位素稀释ICP-MS测定法,对中国东海陆架及日本冲绳海槽的6个沉积物芯中U和Th的同位素地球化学行为进行了研究,以了解氧化还原敏感元素U在近海次氧化性沉积物中的蓄积行为,并评价其在全球海洋铀平衡中的意义。东海沉积物芯中,238U浓度及238U/232Th比值随深度变化不明显。但是在冲绳海槽沉积物芯中,238U浓度及238U/232Th比值在沉积芯表层氧化带显示较低值,然后在次氧化层随深度增加而增加。230Th和232Th浓度在所有沉积物芯中基本不随深度变化。这些结果说明,冲绳沉积物中有“自生铀”的蓄积过程发生,蓄积速率约为(47±5)～(90±8)ng/(cm2·a),与文献报道的世界其他海域次氧化性沉积区大致相当。进一步证明了U在近海次氧化性沉积区的蓄积对于全球海洋铀平衡有重要意义。“自生铀”的主要蓄积机制是海水U(Ⅵ)向沉积物迁移,在还原条件下被还原为惰性的U(Ⅳ)并被吸附在沉积物固体相上。  相似文献   

The optical/near-infrared broad-line emission and hard X-ray continuum of active galactic nuclei and ultraluminous infrared galaxies     

Masatoshi Imanishi †  Shiro Ueno 《Monthly notices of the Royal Astronomical Society》1999,305(4):829-833

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Erratum     

Prof. Masatoshi M. Yoshino 《GeoJournal》1982,6(6):572-572

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Regionality of climatic change in East Asia     

Masatoshi M. Yoshino Prof. Dr.  Urushibara Kazuko 《GeoJournal》1981,5(2):123-132

Regional differences in climatic change are of importance in order to establish the counter-measures for the damage by anomalous climate to agricultural production. It is not unusual for some regions to suffer floods while droughts occur in nearby regions at the same time. This paper deals mainly with the regionality of climatic change in E Asia during recent years, using the year-climate method expressed by the Köppen's system of climatic classification. Occurrence frequencies of BW, BS, Cf, Cw, Dwa, Dwb, and Dwc-type showed striking regionalities, which were obtained from the data at the 134 observatories over E Asia during the period from 1951 to 1970. The distribution of climatic types in each year shows various tendencies: Wet and cold as in 1954 and 1957 shows a pattern in which the boundary between C-type and D-type runs south and the Cfa-zone is broad, extending from middle E China to SW Japan. In contrast, in dry and warm years like 1965, the Dwa regions disappear in the N of E China and the BS region is located just north of the Cwa region, which is distributed broadly from China to Japan. Occurrence frequencies of year climate during the last 100 years were calculated for the 4 stations: Hong Kong, Manila, Shanghai and Tokyo. The results were compared with the distribution types of winter temperature and summer precipitation in China. It seems that the precipitation conditions in summer were reversed between the Philippines and China. Summarizing the results obtained, a schema of the regionality of climatic fluctuation in E and SE Asia was given in relation to the upper air streams. The position of the subtropical jet stream in winter shows a close relationship to the N limit of the Aw and Am year climate regions and in summer with the S limit of Dw region in NE China and North Korea. The Cw and Cf year climate regions in E Asia are located roughly in the regions bounded by the axes of subtropical jet streams in winter and in summer. The Dw year climate region in the E of the Tibetan Plateau reflects the altitudinal effect of the Cw climate of SE China. The N of E China has the variable BS year climate, which may related to the summer and winter jet stream conditions. Finally, the interannual change of the agricultural production index was dealt with in relation to the occurrence frequency of year climate types over E Asia during the years 1967–1970. As far as this period is concerned, the drier conditions are more effective than the wetter conditions in reducing agricultural production.  相似文献   

The gravity-darkening of highly distorted stars in close binary systems     

Masatoshi Kitamura  Yasuhisa Nakamura 《Astrophysics and Space Science》1988,145(1):117-156

From a quantitative analysis of the photometric ellipticity effect, values of the exponent of gravity-darkening have been empirically deduced for the components of sixteen W UMa systems with accurate cross-correlation spectroscopic mass ratios. In the analysis, the exponents for both components of a W UMa system are assumed to be the same. In view of the generally unstable nature of their light curves and the consequent difficulty to find an unique set of the fractional radii of both components, -values have been derived for various equipotential surfaces with boundary cases set at the inner and outer Roche lobes.The results indicate that if the fill-out factors are less than 0.5 (as is so for most of the actual cases), the deduced -values are all greater than Lucy's conventional value of 0.32. The empirical -values as a whole are found to increase with the mean effective temperature of the components and, furthermore, they show a tendency to decrease with increasing mass ratio, particularly for A-type systems. Thus, a W UMa system consisting of two components of quite different masses has a large empirical -value. These observational evidences indicate that the structure of the photosphere of contact components of W UMa systems is significantly different from that of normal Main-Sequence stars of similar spectral type and may provide a clue to solve puzzles of W UMa stars.  相似文献   

Seasonal and Between-Substrate Variation in Mobile Epifaunal Community in a Multispecific Seagrass Bed of Otsuchi Bay, Japan   总被引：2，自引：0，他引：2  

Masahiro Nakaoka  Tetsuhiko Toyohara  & Masatoshi Matsumasa 《Marine Ecology》2001,22(4):379-395

Abstract. A seagrass bed in Otsuchi Bay, northeastern Japan, consists of three seagrass species ( Zostera marina, Z. caulescens and Z. caespitosa ) that differ in morphology and phenology. We studied the mobile epifaunal community in the seagrass bed to examine (1) whether seasonal and between-substrate variation in the epifaunal community agrees with variation in seagrass abundance and morphological complexity, and (2) whether patterns of seasonal and between-substrate variation vary among epifaunal species. We collected mobile epifauna from each of Z. marina and Z. caulescens on 11 occasions between October 1995 and November 1996 (at 1 – 1.5 month intervals) using a hand-closing net. A total of 9 842 individuals of mobile epiphytic animals were collected and they were classified into 80 taxa. Abundance and species richness of the epifaunal community were high in summer to autumn and low in winter to spring, and diversity index and evenness were higher in Z. marina than Z. caulescens . However, patterns of seasonal and between-substrate variation in these parameters did not parallel those in seagrass abundance and complexity. Most of the dominant epifaunal species showed significant seasonal and between-substrate variation in abundance, although their patterns varied greatly among individual species. A cluster analysis recognized several distinct groups of animals showing similar seasonal and between-substrate variation. Our findings suggest that the observed variation in the epifaunal community is not determined by a single or some strong external factors but by complex interactions of multiple factors operating differently for each component species.  相似文献   

Uranium in coastal sediments of Tokyo Bay and Funka Bay   总被引：2，自引：0，他引：2  

Shizuo Tsunogai  Seiya Nagao  Shintaro Watanabe  Yoshiaki Takahashi  Kazunari Suzuki  Masatoshi Yamada  Koh Harada 《Journal of Oceanography》1990,46(5):211-218

The sediment cores from Tokyo Bay and Funka Bay were analyzed for U and its isotopic ratio,²³⁴U/²³⁸U, after dissolving them in 0.1 M HCl, and 30% H₂O₂ in 0.05 M HCl. A small fraction of U in the anoxic sediments was dissolved in 0.1M HCl and even the added yield tracer,²³²U, was lost. The isotopic ratio of H₂O₂ soluble U in the sediments was equal to that of seawater, suggesting that the H₂O₂ soluble U in the sediments is authigenic. The 6M HCl solution dissolved part of the lithogenic U besides the authigenic U. The depth profiles of U from the two bays resembled each other. The authigenic U comprised more than half of the total U even at the surface and increased with depth down to 70 cm, showing small maxima at about 20 cm. The concentration of refractory U was nearly constant with depth and similar to that of the pelagic sediments. The highest U concentration, 6 µg g^–1 which was about 5 times that of the pelagic sediments, was observed in the layer between 70 and 160 cm depth in Tokyo Bay. The annual sedimentation rates of U in the Tokyo Bay sediments were 2.6 tons at the surface and 7.0 tons at the 70–160 cm depth. The increase in U with depth should be due to the deposition of interstitial U either diffusing downward from the surface indicating the trapping of seawater U, or otherwise diffusing upward from the deeper layer indicating the internal cycling of U within the sediments.  相似文献   

砂土边坡深埋桩变形破坏的三维数值分析     

孙德新  彭芳乐  大内正敏  日下部治 《岩土力学》2004,25(Z2):217-222

利用三维弹塑性有限元,对砂土斜坡上刚性深埋桩水平载荷时的变形破坏进行了解析.在有限元解析中,考虑了砂土材料的低抗拉特点.结果表明,有限元计算所得到的桩基水平荷载与水平位移关系与现场实测值基本一致.此外,还利用三维有限元的解析结果,对深埋桩基随深度方向的土压与位移分布以及受压、受拉破坏的渐进性状态进行了合理的分析.  相似文献   

Climatology of yellow sand (Asian sand,Asian dust or Kosa) in East Asia     

Yoshino Masatoshi 《中国科学D辑(英文版)》2002,45(1):59-70

In order to study climatology of yellow sand (Asian sand, Asian dust or Kosa) in East Asia, secular fluctuation in China, Korea and Japan in the recent 30 years was presented. The number of days with sand-dust storm at five stations in China—Hotan, Zhangye, Minqin, Jurh and Beijing, decreases a lot at the former three stations, but changed little at the latter two stations. Suggesting that the recent global warming is more evident in Xinjiang and Gansu, where the frequency of cold air invasions from the higher latitudes is decreasing. But, the eastern parts of Mongolia, inner Mongolia, and North China encounter stronger cyclones in early spring as a result of global warming. These cyclones bring cold air from higher latitudes, causing severe dust storms. Secular variation in the annual days with sand-dust storms in China and Kosa days in Korea and Japan show a parallel change with higher frequency from 1975 to 1985. This may be related to the higher frequency of La Nina years. However, different tendency was shown in the period from 1986 to 1996. Since 1996 or 1997, a sharp increase is clear, which may be caused by the developed cyclones in East Asia as well as human activities, and stronger land degradation under La Nina conditions. Anomalies of the total number of stations with Kosa days were discussed in accordance with some synoptic meteorological conditions such as the differences between Siberian anticyclone and Aleutian cyclone center at 500 hPa level during the previous winter.  相似文献